Somatic embryogenesis efficiency in DNA methylation mutants of Arabidopsis thaliana L.

Somatska embriogeneza (SE) je proces kojim se iz somatske stanice biljke razvija somatski embrij te se naposljetku regenerira čitava biljka. U regulaciji embriogeneze ključnu ulogu ima mehanizam metilacije DNA koji regulira ekspresiju gena i održava stabilnost genoma. Za razliku od animalnih organizama, biljke sadržavaju robusnije mehanizme metilacije DNA te se u njihovom genomu može metilirati bilo koji citozin. Mehanizam metilacije DNA usmjeren malim molekulama RNA (engl. RNA-directed DNA methylation, RdDM) je mehanizam metilacije DNA de novo koji se specifično razvio u biljkama. Poznato je da mutanti za neku od komponenti mehanizma RdDM ispoljavaju aberantni fenotip u različitim stadijima reproduktivnog razvoja tijekom zigotne embriogeneze (ZE), koja dijeli puno sličnosti sa SE. U ovome radu istražena je povezanost mehanizma RdDM i embriogenog potencijala na modelu SE u uročnjaku. Pokazano je da potencijal za indukciju SE ovisi o funkcionalnosti mehanizma RdDM, a tijekom faze sazrijevanja somatskih embrija značaj RdDM-a opada. Ustanovljeno je kako je ekspresija gena povezanih s embriogenezom LEC2, RIE1, MYB115 i ECA1 pod utjecajem mehanizma RdDM. Analizom relativne ekspresije gena LEC2 i RIE1 pokazano je da je kontrola ekspresije LEC2 ovisna o funkcionalnosti RdDM-a tijekom obje faze SE, dok kontrola ekspresije RIE1 o funkcionalnosti RdDM-a ovisi samo tijekom sazrijevanja somatskih embrija.Somatic embryogenesis (SE) is a process in which a somatic plant cell develops into a somatic embryo from which a whole plant can then be regenerated. Mechanism of DNA methylation has a fundamental role in embryogenesis regulation by means of regulating gene expression and maintaining genome stability. Unlike animals, plants possess more robust mechanisms of DNA methylation which can methylate virtually any cytosine in the genome. RNA-directed DNA methylation pathway (RdDM) is a mechanism of DNA methylation de novo specific for plants. Previous research has shown that RdDM mutants show aberrant phenotype in different stages of reproductive development during zygotic embryogenesis (ZE), a process which has many similarities with SE. Here an analysis of embryogenic potential and its dependence on a functional RdDM pathway using a model of SE in Arabidopsis thaliana was conducted. It was shown that the potential for induction of SE depended on a functional RdDM pathway while somatic embryo maturation was less dependent on it. It was also shown that expression of embryogenesis-related genes LEC2, RIE1, MYB115 and ECA1 is regulated by RdDM pathway. Analysis of relative gene expression of LEC2 and RIE1 was performed. Control of LEC2 gene expression was dependent on a functional RdDM pathway during both phases of SE, while control of RIE1 gene expression depended on RdDM pathway only during the maturation phase